An InGaP-HBT IC chipset for 40-Gbps optical transmission systems on the basis of a microwave circuit design scheme

An InGaP-HBT IC chipset for 40-Gbps optical-transmission systems was developed on the basis of a microwave-circuit design scheme techniques, circuit configurations, and concepts. A distributed amplifier achieved ≥50-GHz bandwidth and ≥164-GHz gain-bandwidth product, which are state-of-the-art values for GaAs-HBT-based baseband distributed amplifiers. A compact 40-GHz analog phase shifter with small insertion-loss variation, and 20-GHz/40-GHz clock amplifiers with very low power consumption (about 10 mW) were also realized. Moreover, a new approach - inserting impedance-transformer circuits - to enable ´impedance matching´ in high-speed digital ICs was successfully applied to a 40-Gbps decision circuit to prevent unwanted gain peaking and jitter increase caused by transmission lines without sacrificing chip size.